1. Field of the Invention
The present invention relates to circuit board electrical connectors into which circuit boards are plugged with low insertion forces and, particularly, to a circuit board electrical connector with a latch, which has a slot with contact elements arranged therein and a latch to secure the circuit board inserted into the slot and rotated by a predetermined angle.
2. Description of the Related Art
Recently, electrical connectors for connecting daughter boards having memory elements, etc. to mother boards having electronics components thereon are widely used. There are rotary type zero-insertion force connectors having an insulation housing with an slot into which a daughter board is inserted obliquely and then rotated into a latch portion.
Examples of such a rotary type zero-insertion force connector are disclosed in Japanese patent application Kokai Nos. 229965/92 and 108286/91 and Japanese patent application Kokoku No. 504180/91. A pair of flexible latch levers are provided at opposite ends of the slot of an insulation housing, and latch portions are provided on the upper ends of the latch levers. A daughter board is inserted obliquely into the slot of the insulation housing and then rotated so as to pass the latch portions of the flexible latch levers. When the daughter board passes the latch portions, the flexible latch levers snap the daughter board.
Daughter boards are plugged in the above electrical connectors either vertically or obliquely, but there are some circuit board electrical connectors with a latch, to which daughter boards are plugged in parallel to the mother boards. FIG. 10 shows part of such a circuit board electrical connector with a latch, which is mounted on a mother board.
The electrical connector 2 mounted on a mother board 1 includes an insulation housing 10 with a pair of side walls 12 having latch portions. The latch portions have a first movable arm 15 extending along a fixed portion 14 of the side wall 12, a second movable arm 16 extending from the first movable arm 15 and movable outwardly, and a latch engaging portion 18 extending from the second movable arm 15 to latch a daughter board (not shown) between the portion 18 and the rear wall 19. An operation knob 17 extends from the second movable arm 16. A metal fitting 20A is soldered to the mother board 1 to secure the fixed arm 14 of the side wall 12.
A daughter board is inserted obliquely into a slot provided between the side walls 12 and rotated toward the mother board 1. As the daughter board is rotated, it abuts on upper edges of the engaging portions 18 and flexes outwardly and passes the engaging portions 18. As soon as it passes the engaging portions 18, the movable arms 16 snap the daughter board with lower faces of the engaging portions 18. This completes connection of the daughter board to the electrical connector 2.
The above latch structures, however, lack satisfactory strength in a inward direction. Consequently, it is frequent that the latch portions are broken when the operator moves the latch portions inwardly without any daughter board inserted. In addition, when the latch portions are flexed forwardly, they are frequently broken.